Altitude Sickness
Altitude Sickness or Mountain Sickness, condition caused by reduced oxygen pressure at high altitudes, occurring in hikers as a consequence of relatively rapid ascent to high altitudes. Altitude sickness comprises a range of conditions, the most common being acute mountain sickness, which may be followed by two more critical conditions: high-altitude pulmonary edema or high-altitude cerebral edema.
The exact cause of altitude sickness is unknown, although researchers believe insufficient oxygen may impair the function of the sodium pumps located in cell walls. Without sufficient oxygen, the pumps allow sodium levels within the cell to rise. As a result, excess water enters the cells, causing cellular swelling, or edema, a condition that is especially dangerous in the lungs and around the brain.
The common symptoms of altitude sickness are headache, shortness of breath, sleep disturbances, and sometimes nausea. These symptoms, collectively called acute mountain sickness (AMS), appear in nearly 20 percent of people who ascend higher than about 2400 m (about 8000 ft) above sea level in less than one day. The headache is thought to be caused by cerebral edema. Shortness of breath is caused by a combination of reduced environmental-oxygen pressure and by the swelling and thickening of tissues through which oxygen must pass during respiration.
The symptoms associated with high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE) include those of AMS as well as additional, less common, symptoms. Both HAPE and HACE are more serious conditions than AMS, usually developing after one to four days above about 2700 m (about 9000 ft). Symptoms characterizing HAPE include strong coughing that produces a frothy, sometimes blood-tinged, sputum. The pressure of the blood in the lungs increases, and swollen cells and leaking capillaries allow fluids and red blood cells to enter the air sacs of the lungs, further impeding the delivery of oxygen. Symptoms characterizing HACE include staggering, confusion, and hallucination.
The exact cause of altitude sickness is unknown, although researchers believe insufficient oxygen may impair the function of the sodium pumps located in cell walls. Without sufficient oxygen, the pumps allow sodium levels within the cell to rise. As a result, excess water enters the cells, causing cellular swelling, or edema, a condition that is especially dangerous in the lungs and around the brain.
The common symptoms of altitude sickness are headache, shortness of breath, sleep disturbances, and sometimes nausea. These symptoms, collectively called acute mountain sickness (AMS), appear in nearly 20 percent of people who ascend higher than about 2400 m (about 8000 ft) above sea level in less than one day. The headache is thought to be caused by cerebral edema. Shortness of breath is caused by a combination of reduced environmental-oxygen pressure and by the swelling and thickening of tissues through which oxygen must pass during respiration.
The symptoms associated with high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE) include those of AMS as well as additional, less common, symptoms. Both HAPE and HACE are more serious conditions than AMS, usually developing after one to four days above about 2700 m (about 9000 ft). Symptoms characterizing HAPE include strong coughing that produces a frothy, sometimes blood-tinged, sputum. The pressure of the blood in the lungs increases, and swollen cells and leaking capillaries allow fluids and red blood cells to enter the air sacs of the lungs, further impeding the delivery of oxygen. Symptoms characterizing HACE include staggering, confusion, and hallucination.
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